Production scheduling is an important element of the mine planning
process. The production schedule specifies the quantities of mineral to
extract, the source of this ore, the timing of extraction and, where
necessary, the quantity and timing of backfill placement. These details
are important in linking long-term strategic goals to short-term
operational planning. Mine scheduling techniques form the basis for
communicating information concerning the overall impact of design and
planning changes to a wide range of people at many levels within an
organisation. Consequently the techniques used for mine scheduling must
support the decision-making process by consistently providing high
quality schedules in response to revised and updated data. A new mixed integer programming (MIP) model has been developed to
generate optimal production schedules for underground stoping
operations. The model maximised the before-tax Net Present Value of the
production schedule while satisfying constraints such as contained metal
tonnage, hoisting capacity, stope geometry relationships and stope
backfilling demands. Zero-one variables were used to represent the
decision to extract or backfill each stope in a particular time period.
Continuous variables, capable of having non-integer values, were used to
denote the quantity of ore or backfill associated with a specific stope in a
given time period. A case study is presented to demonstrate the
significant improvement in before-tax NPV over a comparative manual
production schedule in a large underground mine. The MIP model allows
for further modification to reduce solution times and meet the needs of
individual mines.